Why does the gynecologist press down on your lower abdomen during a (non-pregnancy) check up?

I have menstrual issues, and I realized that my lower abdomen was hurting... the same region that the doctor usually presses down on, searching for who knows what. This was in addition to the standard cramps that come with the territory. Let's just say that I've got issues that birth control usually takes care of... but because I had the lower abdominal pain, it just made me wonder what doctors look for when pressing on that region. I'll be heading to the doctor soon, fyi, but I just wanted to know in the meantime. And unless it's by miraculous conception, I'm not pregnant.